Secret Attic Library Door

We have a pretty good guess where [Krizbleen] hides away any seasonal presents for his family: behind his shiny new secret library door. An experienced woodworker, [Krizbleen] was in the process of finishing the attic in his home when he decided to take advantage of the chimney’s otherwise annoying placement in front of his soon-to-be office. He built a false wall in front of the central chimney obstacle and placed a TV in the middle of the wall (directly in front of the chimney) flanked on either side by a bookcase.

If you touch the secret book or knock out the secret sequence, however, the right-side bookcase slides gently out of the way to reveal [Krizbleen’s] home office. Behind the scenes, a heavy duty linear actuator pushes or pulls the door as necessary, onto which [Krizbleen] expertly mounted the bookcase with some 2″ caster wheels. The actuator expects +24V or -24V to send it moving in one of its two directions, so the Arduino Uno needed a couple of relays to handle the voltage difference.

The effort spent here was immense, but the result is seamless. After borrowing a knock-detection script and hooking up a secondary access button concealed in a book, [Krizbleen] had the secret door he’d always wanted: albeit maybe a bit slow to open and close. You can see a video of its operation below.

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Capacitive Christmas Organ with Living Lenses of Slappable Light

We’ve seen capacitive touch organs manifest in pumpkin form. Though they are a neat idea, there’s something about groping a bunch of gourds that stirs a feeling of mild discomfort every time I play one. [mcreed] probably felt the same way and thus created this light-up Jello organ, so he can jiggle-slap Christmas carols, removing any sense of doubt that touching food to play music is weird…

This take on the capacitive tone producing instrument makes clever use of the transparent properties of Jello as well as its trademark wiggling. [mcreed] fills several small mold forms with festively colored strawberry and lime mix. One end of a wire connection is submerged in the liquid of each cup before it has a chance to solidify along with a bright LED. Once chilled and hardened, the gelatinous mass acts as a giant light emitting contact pad. An Arduino is the micro-controller used for the brain, assigning each Jello shape with a corresponding note. By holding onto a grounding wire and completing the acting circuit, one can play songs on the Jello by poking, spanking, or grazing the mounds.

Though I’m not entirely sure if the video is Jello propaganda or not, the idea is applaudable. I prompt anyone to come up with a more absurd item to use for a capacitive organ (zucchinis have already been done).

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Website Response Speedometer

Here’s something that will probably make it to a wall right next to the people responsible for the Hackaday servers sometime soon, and should be something every web dev should build at some point: a website response meter, an analog gauge that will tell you how long it takes to reach your website.

The build is simple enough, with a micro servo working as a gigantic analog gauge. There are also a pair of four-digit, seven-segment displays for displaying a digital number and the number of website requests per second. There’s also an 8×8 matrix of bi-color LEDs for showing a green happy face or a red frowny face, just in case all that data wasn’t self-evident to the uninitiated.

All the electronics are handled by an Arduino, but what really makes this build useful, or even possible, is the bit of code that runs on a computer. The computer uses an API from New Relic, a software analytics company, to come up with the response time and requests per second. That data is pulled down and piped up to the Arduino that displays everything on a beautifully milled acrylic sheet.

Arduino Plays White Tiles On Your Mobile Touchscreen

Like many mobile gamers, [Daniel] has found himself caught up by the addictive “White Tiles” game. Rather than play the game himself though,  [Daniel] decided to write his own automatic White Tiles player. While this hack has been pulled off before, it’s never been well documented. [Daniel] used knowledge he gleaned on Hackaday and Hackaday.io to achieve his hack.

The basic problem is sensing white vs black tiles and activating the iPad’s capacitive touch screen. On the sensing end, [Daniel] could have used phototransistors, but it turned out that simple CdS cells, or photoresistors, were fast enough in this application. Activating the screen proved to be a bit harder. [Daniel] initially tried copper tape tied to transistors, but found they wouldn’t reliably trigger the screen. He switched over to relays, and that worked perfectly. We’re guessing that changing the wire length causes enough of a capacitance change to cause the screen to detect a touch.

The final result is a huge success, as [Daniel’s] Arduino-based player tears through the classic game in only 3.9 seconds! Nice work [Daniel]!

Click past the break to see [Daniel’s] device at work, and to see a video of him explaining his creation.

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Hate Blue M&M’s? Sort Them Using the Power of an iPhone!

Some people really like eating specific M&M colors… You could spend hours sorting your packs of M&M’s into color specific piles, or you could build a machine to do it for you.

That’s exactly what [ReviewMyLife] decided to do, and it’s quite impressive! He’s using a rotating hopper to release M&M’s into a chute one-by-one, and then an iPhone to perform color recognition as the M&M falls past it. That information is then communicated over Bluetooth to the Arduino which actuates a high-speed electromagnetic gate to force the M&M down the right chute for sorting.

The machine works surprisingly well for a prototype that was hot glued together out of foam board, but fear not, he plans to upgrade it now that the proof of concept has been confirmed. He’s hoping to get rid of the iPhone and replace it with a Raspberry Pi for starters, 3D print some of the parts, and consolidate its power supply. Currently he’s using three separate supplies to power the Arduino, electromagnets, and the hopper motor — not very efficient!

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Green-Sweep for Your Ultrasonic Rangefinder

Maybe you’ve never programmed an Arduino before. Or maybe you have, but nothing beyond das blinkenlights. Maybe your soldering iron sits in a corner of your garage, gazing at you reproachfully every time you walk by, like a ball begging to be thrown. Maybe you’ve made a few nifty projects, but have never interfaced them with a PC. If this describes you, then this article and project is just what you need. So grab your favorite beverage, tuck in and prepare to get motivated.

[Anuj Dutt] has not only made a really cool project, he has also done a most excellent job at documenting it. It’s an Arduino controlled “RADAR” like project that uses the familiar Parallax ultrasonic sensor. It’s mounted to a servo and feeds data to a PC where a custom VB.NET program translates the data in to a cool “green radar sweep” screen. It also pushes text to an LCD which reveals the distance from the target.

screenshot of radar program

[Anuj Dutt] hand rolled his Arduino just because, but ran into some trouble getting everything to talk to the PC. He wound up using the ultra user friendly FTDI to save the day. Be sure to check out the video below to see the project in action. [Anuj] published the code for both the Arduino and PC in the video description.

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iRobot Releases Hackable Roomba — Without The Vacuum

We love forward thinking companies that take a risk and do something different. iRobot, the company behind the iconic Roomba, just released the newest version of their Roomba Create — a programmable Roomba (minus the vacuum) that can be hacked and programmed to do all sorts of things.

The company developed the Create with STEM students in mind — a robotics learning platform. It came out originally back in 2007, and we’ve covered many hacks that have made use of it. Many. Like, a lot. One of our favorites has got to be this data center monitoring robot that makes use of the platform!

Anyway, the newest version of the Create features the typical hardware upgrades you’d expect, and with some special emphasis on 3D printing. In fact, the CEO of iRobot [Colin Angle] thinks that 3D printing is going to make a big difference in a few years:

“Your Roomba could be a software file that you print at home,” he says. He says the Create’s new features are a way for the company to get ready for that day, while also providing a platform that educators and hobbyists can use to tinker.

Kudos to you guys, iRobot! We just wish people would stop giving Roomba’s knives…

[Thanks PSUbj21!]